<template>
  <view>
    <text>{{ displayValue }}</text>
  </view>
</template>
<script>
// #ifdef H5
import { requestAnimationFrame, cancelAnimationFrame } from "./xtRequestAnimationFrame.js"
// #endif
// #ifndef H5
let lastTime = 0
// #endif

export default {
  props: {
    startVal: {
      type: Number,
      required: false,
      default: 0,
    },
    endVal: {
      type: Number,
      required: false,
      default: 0,
    },
    duration: {
      type: Number,
      required: false,
      default: 3000,
    },
    autoplay: {
      type: Boolean,
      required: false,
      default: true,
    },
    decimals: {
      type: Number,
      required: false,
      default: 0,
      validator(value) {
        return value >= 0
      },
    },
    decimal: {
      type: String,
      required: false,
      default: ".",
    },
    separator: {
      type: String,
      required: false,
      default: ",",
    },
    prefix: {
      type: String,
      required: false,
      default: "",
    },
    suffix: {
      type: String,
      required: false,
      default: "",
    },
    useEasing: {
      type: Boolean,
      required: false,
      default: true,
    },
    easingFn: {
      type: Function,
      default(t, b, c, d) {
        return (c * (-Math.pow(2, (-10 * t) / d) + 1) * 1024) / 1023 + b
      },
    },
  },
  data() {
    return {
      localStartVal: this.startVal,
      displayValue: this.formatNumber(this.startVal),
      printVal: null,
      paused: false,
      localDuration: this.duration,
      startTime: null,
      timestamp: null,
      remaining: null,
      rAF: null,
    }
  },
  computed: {
    countDown() {
      return this.startVal > this.endVal
    },
  },
  watch: {
    startVal() {
      if (this.autoplay) {
        this.start()
      }
    },
    endVal() {
      if (this.autoplay) {
        this.start()
      }
    },
  },
  mounted() {
    if (this.autoplay) {
      this.start()
    }
    this.$emit("mountedCallback")
  },
  methods: {
    start() {
      this.localStartVal = this.startVal
      this.startTime = null
      this.localDuration = this.duration
      this.paused = false
      // #ifdef H5
      this.rAF = requestAnimationFrame(this.count)
      // #endif
      // #ifndef H5
      this.rAF = this.requestAnimationFrame1(this.count)
      // #endif
    },
    pauseResume() {
      if (this.paused) {
        this.resume()
        this.paused = false
      } else {
        this.pause()
        this.paused = true
      }
    },
    pause() {
      // #ifdef H5
      cancelAnimationFrame(this.rAF)
      // #endif
      // #ifndef H5
      this.cancelAnimationFrame1(this.rAF)
      // #endif
    },
    resume() {
      this.startTime = null
      this.localDuration = +this.remaining
      this.localStartVal = +this.printVal
      // #ifdef H5
      requestAnimationFrame(this.count)
      // #endif
      // #ifndef H5
      this.rAF = this.requestAnimationFrame1(this.count)
      // #endif
    },
    reset() {
      this.startTime = null
      // #ifdef H5
      cancelAnimationFrame(this.rAF)
      // #endif
      // #ifndef H5
      this.cancelAnimationFrame1(this.rAF)
      // #endif
      this.displayValue = this.formatNumber(this.startVal)
    },
    count(timestamp) {
      if (!this.startTime) this.startTime = timestamp
      this.timestamp = timestamp
      const progress = timestamp - this.startTime
      this.remaining = this.localDuration - progress

      if (this.useEasing) {
        if (this.countDown) {
          this.printVal =
            this.localStartVal - this.easingFn(progress, 0, this.localStartVal - this.endVal, this.localDuration)
        } else {
          this.printVal = this.easingFn(
            progress,
            this.localStartVal,
            this.endVal - this.localStartVal,
            this.localDuration
          )
        }
      } else {
        if (this.countDown) {
          this.printVal = this.localStartVal - (this.localStartVal - this.endVal) * (progress / this.localDuration)
        } else {
          this.printVal = this.localStartVal + (this.endVal - this.localStartVal) * (progress / this.localDuration)
        }
      }
      if (this.countDown) {
        this.printVal = this.printVal < this.endVal ? this.endVal : this.printVal
      } else {
        this.printVal = this.printVal > this.endVal ? this.endVal : this.printVal
      }

      this.displayValue = this.formatNumber(this.printVal)
      if (progress < this.localDuration) {
        // #ifdef H5
        this.rAF = requestAnimationFrame(this.count)
        // #endif
        // #ifndef H5
        this.rAF = this.requestAnimationFrame1(this.count)
        // #endif
      } else {
        this.$emit("callback")
      }
    },
    isNumber(val) {
      return !isNaN(parseFloat(val))
    },
    formatNumber(num) {
      num = num.toFixed(this.decimals)
      num += ""
      const x = num.split(".")
      let x1 = x[0]
      const x2 = x.length > 1 ? this.decimal + x[1] : ""
      const rgx = /(\d+)(\d{3})/
      if (this.separator && !this.isNumber(this.separator)) {
        while (rgx.test(x1)) {
          x1 = x1.replace(rgx, "$1" + this.separator + "$2")
        }
      }
      return this.prefix + x1 + x2 + this.suffix
    },
    requestAnimationFrame1(callback) {
      const currTime = new Date().getTime()
      // 为了使setTimteout的尽可能的接近每秒60帧的效果
      const timeToCall = Math.max(0, 16 - (currTime - lastTime))

      const id = setTimeout(() => {
        callback(currTime + timeToCall)
      }, timeToCall)

      lastTime = currTime + timeToCall
      return id
    },

    cancelAnimationFrame1(id) {
      clearTimeout(id)
    },
  },
  destroyed() {
    // #ifdef H5
    cancelAnimationFrame(this.rAF)
    // #endif
    // #ifndef H5
    this.cancelAnimationFrame1(this.rAF)
    // #endif
  },
}
</script>
